Block
11 Index Files

Unlike an image
index file, which describes a complete image, a new Block 11 index file is
created every 10 minutes. The time portion of the Block 11 index file's name
is the time the index file was created. Unlike the image index files, the time
in the Block 11 index name is a local workstation time. When a Block 11 is
located in an SDF file, an entry is made in the current Block 11 index file.
Block 11 index files are in ASCII format and therefore can be viewed using
most unix file viewing commands.

The naming
convention for the Block 11 index files is:

gvar.ccyy.ddd.hhmm.B11

Where:

cc

is
the century when the image started

yy

is
the year when the image started

ddd

is
the Julian day when the image started

hh

is
the UTC hour when the image started

mm

is
the minute when the image started

Every entry
in the Block 11 index file identifies a data block in an SDF file and it's
location within the SDF file. As in the imager index files, sync errors and
slipped bits are also logged in the Block 11 index file entries.

The fields
in the Block 11 index have the same meanings as the imager index.